CA2091857A1 - Process and apparatus for manufacturing low-gas and pore-free aluminum casting alloys - Google Patents

Process and apparatus for manufacturing low-gas and pore-free aluminum casting alloys

Info

Publication number
CA2091857A1
CA2091857A1 CA002091857A CA2091857A CA2091857A1 CA 2091857 A1 CA2091857 A1 CA 2091857A1 CA 002091857 A CA002091857 A CA 002091857A CA 2091857 A CA2091857 A CA 2091857A CA 2091857 A1 CA2091857 A1 CA 2091857A1
Authority
CA
Canada
Prior art keywords
vacuum
melt
continuous casting
furnace
casting mold
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Abandoned
Application number
CA002091857A
Other languages
French (fr)
Inventor
Heinz Lorenz
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Vaw Aluminium AG
Original Assignee
Vaw Aluminium AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Vaw Aluminium AG filed Critical Vaw Aluminium AG
Publication of CA2091857A1 publication Critical patent/CA2091857A1/en
Abandoned legal-status Critical Current

Links

Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22DCASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D27/00Treating the metal in the mould while it is molten or ductile ; Pressure or vacuum casting
    • B22D27/15Treating the metal in the mould while it is molten or ductile ; Pressure or vacuum casting by using vacuum
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22DCASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/10Supplying or treating molten metal
    • B22D11/11Treating the molten metal
    • B22D11/113Treating the molten metal by vacuum treating
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22DCASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D21/00Casting non-ferrous metals or metallic compounds so far as their metallurgical properties are of importance for the casting procedure; Selection of compositions therefor
    • B22D21/002Castings of light metals
    • B22D21/007Castings of light metals with low melting point, e.g. Al 659 degrees C, Mg 650 degrees C
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22BPRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B21/00Obtaining aluminium
    • C22B21/06Obtaining aluminium refining
    • C22B21/068Obtaining aluminium refining handling in vacuum

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Continuous Casting (AREA)
  • Casting Support Devices, Ladles, And Melt Control Thereby (AREA)

Abstract

ABSTRACT OF THE DISCLOSURE

The invention relates to a process and apparatus for manufacturing low-gas and pore-free aluminum casting alloys by vacuum treatment of the melt. Contact between the aluminum melt and the atmospheric humidity of the alloying process, from refining to continuous casting of the cast bars, is kept extremely short, so that environmentally-friendly and effective vacuum degasification, and a high cooling rate, can prevent the formation of gas pores.
After the metal melt is alloyed in a smelting furnace, the melt is fed through a system of gutters directly to at least one vacuum furnace. Refining components are added in the vacuum furnace and the pouring temperature required for continuous casting is adjusted. The vacuum in the vacuum furnace is maintained to degasify the melt and increase the density thereof, such as for an additional 5 to 240 minutes with periodic measurements of the metal density, and the metal melt is then fed through the gutter system directly to the continuous casting mold.

Description

PROCE~S AND APP~RATUS FOR M~NUFACTURING
LOW-G~S AND PORE-FREE ALUMINUM C~STING ALLOYS

BACKGROUND OF THE INVENTION

Fleld of the Invention:

The invention relates to a process and an apparatus for manufacturing low-gas and pore-free aluminum casting alloys. Crucible or tank-type furnaces qenerally are used to make casting alloys. Either liquid electrolysis metal is loaded or solid metal is smelted. The des~red alloy composition is adjusted by adding alloy components such as silicon, magnesium, copper, titanium and/or nickel. The smelting bath is heated to dissolve and alloy the components. Increased amounts of hydrogen are absorbed because aluminum in the liquid state has a high dissolving capacity for hydrogen. The latter is produced by the reaction of liquid aluminum with steam and is immediately absorbed atomically by the melt. The steam comes in contact with the molten aluminum through the materials used, the jackets of the oven and crucible, the tools, the melting auxiliaries and flux, the combustion of gaseous and liquid fuels, and the atmospheric humidity. The amount of hydrogen di~solved depends on the temperature of the metal, the composition of the alloy, and the partial pressure of the hydrogen. The hydrogen upta~e is favored by open burner ~lames or vigorous bath movements in induction furnaces. In the refining of casting alloys with alkali and alkaline earth metals such as strontium, sodium and calcium, the h~vdrogen content of the melt increases considerably to values of more than 0.3 ml hydrogen per 100 g of metal, since steam decomposes even more rapidly under the influence of these metals. Ihe melt should be purified immediately before pouring if possible, since treatment performed too early can lead to contamination once again during subsequent technological steps, for example pouring to transport the melt. In particular, the melt coming in contact with the humidity in the atmosphere results in an increase in hydrogen content and the resultant undesirable increased porosity of the aluminum castlngs. Usual purification processes are performed with inert as well as chemically-active gases. During flushing with inert gases (argon or nitrogen, for example), the hydrogen is practically physically removed by lowering its partial pressure. This type of hydrogen removal is expensive from the technical standpoint and poses the risk of hydrogen coming in contact with the melt during treatment. In addition, undesirable nitride formation can occur when nitrogen is used with certain alloy components. When chemically active chlorine gas is employed, aluminum chloride is formed and rises to the surface; it produces effective flushing because of its distribution in the~melt.
Chlorine gas is a serious environmental poison, however, and is also expensive to manufacture. The protective measures required to prevent the escape of the poisonous gas and its reaction products require considerable investment. In contrast to the use of chemical agents, vacuum degasification of the melt is especially environmentally friendly and effective method. However, this method is not optimally successful, mainly because of the costly transportation of the melt, intermediate cooling and remelting after the necessary alloying, re~ining, and vacuum degasification processes, ur.til continuous casting takes place and the necessary coming into contact with the atmospheric humidity which that involves, so that the alloying and refining process followed by continuous casting does not produce gas-poor and pore-free aluminum casting alloys.

SUMMARY OF THE INVENTION

The present invention provides a process and an apparatus for manufacturing low-gas and pore-free aluminum casting alloys in which contact between the aluminum melt and the atmospheric humidity of the alloying process is maintained extremely low through refining to continuous casting of the 2 ~ ; r~l cast bars, so that environmentally-friendly and effective vacuum degassing can be used and the formation o~ large gas pores prevented by a high cooling rate.

THE DRAWING

Figure 1 is a diagrammatic illustratlon of an apparatus composed of a smelting furnace, two vacuum smelting furnaces, and one horizontal continuous casting system with a ceramic mold filter, all linked by a system of gutters or troughs for the gravity flow of molten alloy:

Figure 2 is a cross section of a pig or castLng made of metallurgical alloy poured on a prior known water-cooled pig-casting machine, illustrating the large pore content thereof, and Figure 3 is a cross section through a continuous-cast bar, cast according to the process of the present invention and using the apparatus of the present invention.

DETAILED DESCRIPTION

According to the present invention, alloys of reduced poro~ity are produced by alloying the metal melt in a smelting furnace, guiding the smelted alloy melt through a system of gutters directly to at least one vacuum furnace wherein refining components are added, and the pouring temperature required for continuous casting is adiusted.
The vacuum in each vacuum furnace is maintained for another 5 to 240 minutes, with periodic measurement of the metal density, and at this point the molten metal is fed through the gutter system directly to the continuous casting system, with the molten metal being filtered prior to entering the continuous casting mold. According to the invention, the melt is guided from the smelting furnace through the gutter system alternately or simultaneously into two vacuum furnaces, so that the continuous casting r~

system, preferably a horizontal continuous casting mold, can be fed continuously with melt. For optimum qualitative and quantitative performance of the process, it is important that the density of the metal be measured during holding in the vacuum furnace. This makes it possible to control the residence time of the melt under vacuum conditions. It is advantageous that during the holding of the vacuum, the level of the vacuum remains between 100 and 1 mbar.

Regulation of the duration of the vacuum depends primarily on the metal density values measured. Thus, it may be absolutely necessary to maintain or to vary the vacuum during holding. For example, it is advantageous t~hat a value for the vacuum during holding that is as high as possible be set as the density of the metal increases, so that hydrogen can be expelled by reducing its partial pressure further, despite increasing metal density.

By using a water-cooled horizontal continuous casting mold that is loaded quic~ly, and with relatively short travel for the melt from the vacuum furnace, a high cooling rate is likewise achieved that prevents formation of large pores. The arrangement of the smelting furnace, at least one vacuum smelting furnace, and the continuous casting mold, which are linked directly together by a system of gutters, makes it possible to keep the metal always in the molten state during the treatment process. Energy-intensive hardening and remelting processes are eliminated by optimum transportation of the melt through the gutter system. To facilitate the flow of the melt through the gutter system by gravity, a slope is provided by locating the furnace and the continuous casting system on different levels or by using a height-adjustable gutter system. The gutter system according to the invention is an open system so that the flow of the melt can be observed at any time.
Because of the short distance involved, contact of the melt with atmospheric humidity is minimal.

~eferring to the drawing, the smelting furnace 1 in Figure 1 generally is a crucible or tank-type furnace. It serves to make the alloy. The alloy components such as silicone, magnesium, copper, titanium, nickel, etc. are batched, and a refining treatment with reactive or inert gas is performed, and the metal temperature required to transfer the melt to vacuum furnace 2 is set. The melt flows downhill from furnace 1 under the influence of gravity through gutter section 4a into the two vacuum furnaces 2.
The capacity of furnace 1 is so great that both vacuum furnaces 2 can be loaded alternately through gutter sections 4b and 4c. The refining components such as strontium, sodium, and calcium are alloyed here at the necessary temperature set to reflect the predete~rmined pouring temperature. In vacuum furnace 2, the alloy melt is subjected to a vacuum treatment controlled in accordance with the results of the metal density test. Following a positive density test, the melt is fed through sections 4b and 4c, from the two vacuum furnaces 2 sequentially, through the gutter system and through an interposed ceramic mold filter 5, to water-cooled horizontal continuous casting system 3, and cast to form standard bars. The low-gas, pore-free cast alloys thus produced make lt possible with proper remelting to turn out ductile pore-free castings.

The gutter or trough system of Fig. 1 contains multiple connections 4a, 4b and 4c, each of which i9 adjustable heightwise to control the direction of gravity flow of the molten metal from the smelting furnace 1 to either or both of the vacuum alloying furnaces 2, and from either or both of the vacuum alloying furnaces 2 to the filter 5 and mold 3.

Castings of alloys produced according to the prior art process and casting apparatus contain a high degree of porosity due to a large amount of non-liberated gas, as illustrated by Fig. 2 of the drawing, whereas castings of ~ 7 similar alloys produced by the present process and apparatus are substantially gas-free and non-porous, as illustrated by Fig. 3.

It should be understood that the foregoing description is only illustrative of the invention. Various alternatives and n)odi~ications can be devised by those skilled in the art without departing from the invention. Accordingly, the present invention i5 intended to embrace all such alternatives, modifications and variances whlch fall within the scope of the appended claims.

Claims (15)

1. Process for manufacturing low-gas and pore-free aluminum casting alloys by vacuum treatment of the melt, characterized by the steps of (a) alloying the metal melt in a smelting furnace, (b) feeding the melt directly to a vacuum furnace through a gutter system, (c) adding refining components, (d) heating to a casting temperature necessary for continuous casting, (e) maintaining a vacuum in the vacuum furnace to increase the density of the melt, and (f) feeding the high density metal melt directly to a continuous casting mold through another section of said gutter system.
2. Process according to Claim 1 characterized by the step of filtering the metal melt before it enters the continuous casting mold.
3. Process according to Claim 1 characterized by the melt being supplied from the smelting furnace through the gutter system alternately or simultaneously to two vacuum furnaces.
4. Process according to Claim 1 characterized by the step of briefly interrupting the vacuum in the vacuum furnace to measure the metal density.
5. Process according to Claim 1 characterized by the level of the vacuum being between 100 and 1 mbar during the holding of the vacuum.
6. Process according to Claim 1 characterized by the fact that the level of the vacuum is kept constant while the vacuum is maintained.
7. Process according to Claim 1, characterized by the fact that the level of the vacuum is varied while the vacuum is maintained.
8. Process according to Claim 1, characterized by the intensity of the vacuum treatment being correlated to the metal density.
9. Process according to Claim 1, characterized by the duration of the vacuum being increased with increasing metal density.
10. Apparatus for making low-gas and pore-free aluminum casting alloys, consisting of a smelting furnace, at least one vacuum smelting furnace, and a continuous casting mold, characterized by the smelting furnace, each vacuum smelting furnace and the continuous casting mold being connected in with one another through a gutter system, a filter located upstream of the continuous casting mold, said filter, when connected to a plurality of vacuum smelting furnaces, being positioned substantially at a mid-point of the gutter connecting the plurality of vacuum smelting furnaces.
11. Apparatus according to Claim 10 characterized by the level of the smelting furnace being above the level of each vacuum smelting furnace and of the continuous casting mold.
12. Apparatus according to Claim 10 characterized by the continuous casting mold being a horizontal casting mold.
13. Apparatus according to Claim 10 characterized by the gutter system being open to permit observation of the melt.
14. Apparatus according to Claim 10 characterized by parts of the gutter system located between the smelting furnaces being provided with multiple connections which are adjustable heightwise.
15. Apparatus according to Claim 10 characterized by said filter being a ceramic mold filter.
CA002091857A 1992-04-18 1993-03-17 Process and apparatus for manufacturing low-gas and pore-free aluminum casting alloys Abandoned CA2091857A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DEP4212936.2 1992-04-18
DE4212936A DE4212936C2 (en) 1992-04-18 1992-04-18 Process and arrangement for producing low-gas and non-porous cast aluminum alloys

Publications (1)

Publication Number Publication Date
CA2091857A1 true CA2091857A1 (en) 1993-10-19

Family

ID=6457057

Family Applications (1)

Application Number Title Priority Date Filing Date
CA002091857A Abandoned CA2091857A1 (en) 1992-04-18 1993-03-17 Process and apparatus for manufacturing low-gas and pore-free aluminum casting alloys

Country Status (13)

Country Link
US (1) US5330555A (en)
EP (1) EP0566867A1 (en)
KR (1) KR930021294A (en)
AU (1) AU3693993A (en)
CA (1) CA2091857A1 (en)
CZ (1) CZ61593A3 (en)
DE (1) DE4212936C2 (en)
HU (1) HUT65416A (en)
NO (1) NO931049L (en)
SK (1) SK34193A3 (en)
TR (1) TR26957A (en)
TW (1) TW242588B (en)
ZA (1) ZA931909B (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113684402A (en) * 2021-09-01 2021-11-23 连云港星耀材料科技有限公司 Preparation method and processing equipment of rare earth aluminum alloy steering knuckle with good toughness

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1041900C (en) * 1994-10-20 1999-02-03 邱表来 Vacuum extrusion and special heat treatment technology for producing high-strength shockproof aluminium casting
CN103436919B (en) * 2013-08-22 2016-06-01 中冶东方工程技术有限公司 A kind of preliminary cleaning method before high-temperature electrolysis aluminium liquid founding and product
CN105087968A (en) * 2014-05-13 2015-11-25 陕西宏远航空锻造有限责任公司 Optimized production method for producing aluminum alloy casting through vacuum melting and casting
CN112795803B (en) * 2020-12-27 2022-06-28 上海交通大学安徽(淮北)陶铝新材料研究院 In-situ self-growing aluminum-based composite material system with powder injection

Family Cites Families (8)

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Publication number Priority date Publication date Assignee Title
DE2029687A1 (en) * 1970-06-16 1971-12-23 Deutsche Edelstahlwerke AG, 4150Krefeld Process for casting metal or metal alloys in continuous casting molds
US4049248A (en) * 1971-07-16 1977-09-20 A/S Ardal Og Sunndal Verk Dynamic vacuum treatment
JPS5556077A (en) * 1978-10-21 1980-04-24 Bridgestone Tire Co Ltd Ceramic porous body
JPS5967350A (en) * 1982-10-08 1984-04-17 Toshiba Corp Aluminum material
CA1226717A (en) * 1984-05-16 1987-09-15 William L. Sherwood Continuous vacuum degassing and casting of steel
JPS61186150A (en) * 1985-02-13 1986-08-19 Sumitomo Light Metal Ind Ltd Casting method by suspension in electromagnetic field
JPH0620618B2 (en) * 1985-03-26 1994-03-23 日立電線株式会社 Continuous casting method and apparatus
US4738717A (en) * 1986-07-02 1988-04-19 Union Carbide Corporation Method for controlling the density of solidified aluminum

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113684402A (en) * 2021-09-01 2021-11-23 连云港星耀材料科技有限公司 Preparation method and processing equipment of rare earth aluminum alloy steering knuckle with good toughness
CN113684402B (en) * 2021-09-01 2022-11-22 连云港星耀材料科技有限公司 Preparation method and processing equipment of rare earth aluminum alloy steering knuckle with good toughness

Also Published As

Publication number Publication date
US5330555A (en) 1994-07-19
ZA931909B (en) 1994-01-19
SK34193A3 (en) 1993-11-10
EP0566867A1 (en) 1993-10-27
DE4212936A1 (en) 1993-10-21
TW242588B (en) 1995-03-11
CZ61593A3 (en) 1993-12-15
TR26957A (en) 1994-09-12
HUT65416A (en) 1994-06-28
NO931049D0 (en) 1993-03-23
NO931049L (en) 1993-10-19
KR930021294A (en) 1993-11-22
AU3693993A (en) 1993-10-21
HU9301124D0 (en) 1993-08-30
DE4212936C2 (en) 1994-11-17

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Legal Events

Date Code Title Description
EEER Examination request
FZDE Discontinued